On the Scalability of Path Exploration Using Opportunistic Path-Vector Routing

Hasan T. Karaoglu,Murat Yuksel, Mehmet H. Gunes

University of Nevada, RenoICC’11 NGNI, Kyoto

June, 2011

MotivationRising Trends for Communication

Customizable – On Demand Network Services Software Defined Networking (OpenFlow, IPSphere,

GENI), Cognitive Radio, CDN, “Routing As a Service” Multi-dimensional Routing Problem

Application specific (VPN, CDN), Economics – Value components, Security, Mobility, Energy-Aware

Dynamism (Mobility, Time Granularity)

ImplicationsComplexity & Scale Problems, Lack of Coordination

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Research QuestionThese implied challenges have been

considered before: Wireless & MANET & Complex Networks

“Can we apply some of the lessons learnt into Wired, Inter-domain Routing Area?” Distributed Mechanisms Loose Coordination Relaxed Determinism Dynamism and Diversity

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Outline

• Motivation• Research Question• Opportunistic Path Vector Routing• Routing Mechanisms• Evaluation• Improvements• Conclusion

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Opportunistic Path Vector Routing

5

User X

2

3

5

ISP A

ISP C

ISP B

1 4

[5, A-B, 1-2-4, 15-20Mb/s, 20-30mins, $4]

[5, A, 1-2, 15-30Mb/s, 15-30mins, $8]

[5, A, 1-3, 5-10Mb/s, 15-20mins, $7]

• Paths to 5 are found and ISP C sends replies to the user with two specific contract-path-

vectors.

path request path request

path request

[A-B-C, 1-2-4-5, 20Mb/s, 30mins]

[A-C, 1-3-5, 10Mb/s, 15mins]

Paths to 5 are found and ISP C sends

replies to the user with two specific contract-

path-vectors.

replyreply

reply

[5, 10-30Mb/s, 15-45mins, $10]

Opportunistic Path Vector Routing

IETF - Path Computation Element (PCE) WG– GMPLS, Inter-domain QoS, (Nested LSP or LSP Stitching)– RFC 4655: Architecture, 5376: Reqs, 5441: BRPC– Path Discovery along given AS_PATH– Limited Scale, Computational and Storage Cost Problems

Solution Proposals S. Secci et al., “AS-level source routing for multi-provider connection-oriented

services” Computer Networks 54, 14 (October 2010) F. Cugini et al., "PCE Communication Protocol for Resource Advertisement in

Multi-Domain BGP-Based Networks“, OWL3, 2009.

Alternative Approach: Parametric Gossip? Flooding > Gossip > Random Walks Sensor Networks, Vehicular Networks

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• Gossiping: Making distribution of path discovery packets a parametric probabilistic process

• Parameters: Resource Availability, Risk Perception, Economic Concerns, ISP Policy, Overall Discovery Packet Traffic Load (Filtering)

• Probabilistic Approach: Not Arbitrary, well-studied theoretical properties (Check Percolation Theory and Belief Propagation)

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Opportunistic Path Vector Routing

Forwarding Mechanisms

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Destination in Local

Neighborhood

PATH INQUIRY

Bloom Filter Based Recursive

Route Resolution

YES

NEXT HOP

NO

Smart Randomized Forwarding

• Parametric Gossiping• Select a subset of neighbors

1) ISP Policy

2) Traffic Engineering

3) Pure Random• Forward Path Inquiry

Forwarding Mechanisms

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bTTL: How many copies of discovery packet will be made and forwarded? Provides caps on messaging cost.

dTTL: Time to Live, Hop-Count Limit

MAXFWD: Max. number of neighbors to be forwarded

Forwarding Mechanisms

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• Procedure to check if destination is within two-hop neighborhood– Bloom Filters: Efficient, Fast Group Membership

Storage / Control Method for locality database– M Bloom Filter for M discovery region– False Positives result in Smart-Randomized

Forwarding• Nice balance between locality storage cost

and messaging cost of flooding

Evaluation

• CAIDA, AS-level, Internet Topology as of January 2010 (33,508 ISPs)

• Trial with 10000 ISP Pair (src,dest), 101 times• With various ISP cooperation / participation

and packet filtering levels– NL: No local information used– L: Local information used (with various filtering)

• With no directional and policy improvements for base case (worst) performance

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Results – Path Exploration

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Over 80% path exploration success ratio even at 50% discovery packet filtering thanks to

diversity of Internet routes.

With Locality, OPVR achieves near 100

percent path exploration success.

As budget increases with BTTL and

MAXFWD, OPVR becomes robust to

filtering

Results - Diversity

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Tens of paths discovered favoring

multi-path routing and reliability schemes.

Results – Path Stretch

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Results – Messaging Cost

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Number of discovery packet copies is well

below theoretical bounds thanks to path-vector loop

prevention.

Results – Transmission Cost

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Conclusion

• OPVR’s Messaging Based Query Methods can be a better option – Advantages: Distributed, Light-Computation– Disadvantages: Less deterministic, Message Cost

• Gossiping Method: – Diverse Path Exploration, – Controllable Messaging Cost, – Robust to Filtering – Allows parametric, fine-grained policy definitions– Dynamic

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Improvements

• Directional Gossiping (P2P or P2M)– Structured AS Path Exploration– No-valley Rule

• Cache– Similar to DNS cache

• Business Alliances Model– Clusters of ISPs as business partners– Revisiting HLP model, customer cone

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Questions?

Thank YouFor offline question: karaoglu@cse.unr.eduGoogle “Contract Switching” http://www.cse.unr.edu/~yuksem/contract-switching.htm

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